Biofuels derived from lignocellulosic biomass represent an alternative to petroleum based transportation fuels that take advantage of an abundant and renewable resource while not utilizing food crops as feedstocks. Cellulose and hemicellulose found in biomass, however, must first be converted to fermentable sugars, which are in turn converted to biofuels such as ethanol by fermentative organisms.
Numerous methods have been developed to convert biomass cellulose and hemicellulose fractions to sugars, including treatment with enzymes or chemicals. Pretreatment of biomass feedstocks with dilute acid is a technique frequently used to hydrolyze hemicellulose and improve the susceptibility of cellulose to enzymatic degradation, but this process can create compounds that inhibit the subsequent fermentation of sugars to biofuels. Methods to detoxify the pretreated feedstocks are often not economical or reduce the amount of sugars available for fermentation.
The existence of multiple inhibitors within feedstocks such as corn stover treated with dilute sulfuric acid restrains the growth of biocatalyst organisms leading to low ethanol yield and/or prolonged fermentation processes. Development of robust biocatalysts with enhanced tolerance to feedstock inhibitor compounds is needed for the economical production of biofuels.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.